1. Field of the Invention
This invention relates to an engine starting control apparatus that cranks an engine by means of a starter motor to start the engine, and more particularly to an engine starting control apparatus that cranks, upon starting of an engine, a crankshaft in the reverse direction to a predetermined position to improve the startability of the engine.
2. Description of Background Art
The official gazette of Japanese Patent Laid-open No. Sho 63-75323 discloses an engine stopping and starting control apparatus which controls an engine so that the engine is automatically stopped when a vehicle stops and re-started. Starting control is accomplished when a throttle grip is operated in the stopping state of the vehicle to issue an instruction to start the vehicle, and has the effect of reducing the production of exhaust gas or consumption of the fuel, particularly during idling. As a result, this device provides some environmental and energy saving benefits.
Another device is disclosed, for example, in the official gazette of Japanese Patent Laid-open No. Hei 6-64451, or the official gazette of Japanese Patent Laid-open No. Hei 71350. This device uses a technique of rotating a crankshaft reversely to a predetermined position before an engine is started, and then starting the engine from the reversely rotated position. As such, this device helps to reduce the cranking torque upon starting of the engine, thus enhancing the startability of the engine.
However, the above devices are not without problems.
In a four-cycle engine, it is sufficient if ignition is performed at the compression top dead center, and ignition is not necessary at the exhaust top dead center. However, for the reason that it is necessary to discriminate a stroke in order to cause ignition to occur only at the compression top dead center and that there is no actual loss even if ignition occurs at the exhaust top dead center, ignition is usually performed as useless ignition at the exhaust top dead center.
However, if the reverse rotation control described above is applied, since fuel air mixture remaining in the exhaust pipe is sucked into the cylinder in the exhaust stroke upon the reverse rotation, there is the possibility that the air fuel mixture may be fired by useless ignition at the exhaust top dead center upon subsequent forward rotation.
It is an object of the present invention to solve the problems of the prior art described above by providing an engine starting control apparatus which is capable of preventing firing by useless ignition with a simple and inexpensive configuration that does not need a system for discrimination of a stroke, or the like.
In order to attain the object described above, the present invention adopts the following countermeasures for an engine starting control apparatus; namely, upon starting of an engine, a crankshaft is caused to rotate reversely to a predetermined position, and then rotate forwardly.
Several characteristics of the present invention are described below:
(1) The engine starting control apparatus of the present invention includes a starter motor connected to the crankshaft, ignition means for igniting the engine in the proximity of the top dead center of a piston, and ignition suppression means for inhibiting the ignition of the engine for a predetermined period of time after the forward rotation of the engine.
(2) In the engine starting control apparatus of the present invention the reverse rotation control means causes the crankshaft to rotate reversely until the piston runs over the exhaust top dead center.
(3) In the engine starting control apparatus of the present invention the engine has a valve overlap period within which an intake valve and an exhaust valve communicate with each other in the proximity of the exhaust top dead center, and the ignition means inhibits ignition and causes the engine to misfire at a position in the proximity of the exhaust top dead center.
(4) In the engine starting control apparatus of the present invention the ignition suppression means inhibits ignition of the engine only for the first ignition timing after the engine is rotated forwardly.
(5) Further, the engine starting control apparatus of the present invention includes a kick starting means for causing the crankshaft to rotate forwardly using man-power, and an ignition suppression cancellation means for canceling the inhibition of the ignition of the engine by the ignition suppression means when the engine is started by man-power.
With the characteristic (1) described above, even if air fuel mixture remaining in the exhaust pipe is sucked into the cylinder in an exhaust stroke during the reverse rotation and is compressed at the exhaust top dead center during the forward rotation thereafter, since ignition is inhibited at the timing, firing of the air fuel mixture is prevented. Accordingly, firing by useless ignition is prevented by using a simple and inexpensive ignition means. Moreover, the apparatus has high flexibility and avoids the need to perform a stroke discrimination operation.
With the characteristic (2) described above, since the crankshaft always is rotated forwardly and reversely on reaching the boundary of the exhaust top dead center, the running start distance upon forward rotation can be assured sufficiently. Accordingly, firing by useless ignition can be prevented while maintaining good startability.
With the characteristic (3) described above, firing by useless ignition can also be prevented in a structure wherein, when the crankshaft stops in the proximity of the exhaust top dead center, the intake system, the combustion chamber and the exhaust system communicate with each other, which makes it likely that the combustible air fuel mixture flows into the exhaust system, as with a high output power engine having a valve overlap period.
With the characteristic (4) described above, since ignition is inhibited only with regard to the first useless ignition, rapid firing by normal ignition can be achieved. Accordingly, firing by useless ignition can be prevented without sacrificing the startability.
With the characteristic (5) described above, since misfiring is not inhibited upon cranking from a state wherein the crankshaft is not rotated reversely as upon kick starting, the startability upon kick starting is not disturbed by unnecessary inhibition of ignition.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.